Free piston machine



June 14, 1966 A. BRAUN 3,255,741

FREE PISTON MACHINE Original Filed Nov. 21, 1960 United States Patent 3,255,741 FREE PISTON MAQHINE Anton Eraun, 338 Arrowhead Place, Kingston, Ontario, Canada Original application Nov. 21, 1960, See. No. 70,650. Divided and this application Feb. 24, 1964, Ser. No.

3 Claims. (El. 12346) This invention relates to free piston machines. This application is a division of application Serial Number 70,650, filed November 21, 1960, now Patent No. 3,134,- 372 issued May 26, 1964.

It is usual, in free piston machines, to provide the required air or gas ducts externally of the machine casing. Obviously, this ducting substantially increases the overall size of the machine and, of course, interferes with the compact, symmetrical design of the'machine.

It is an object of this invention to provide a free piston machine wherein the ducting is incorporated within the machine casing to provide a more compact machine of substantially symmetrical design. v

The invention will be described with reference to the accompanying drawing, in which FIGURE 1 is a sectional side elevation of a free piston engine in accordance with the invention,

FIGURE 2 is a section on line 2-2 of FIGURE 1,

FIGURE 3 is a section on line 33 of FIGURE 1,

FIGURE 4 is a side elevation, partly in section, of a modified form of free piston engine, and

FIGURE 5 is a section on line 5-5 of FIGURE 4.

Referring to FIGURES l, 2 and 3, the engine shown is housed within a generally cylindrical casing 141. Concentrically arranged within the casing is a hollow cylindrical or tubular member 142 which provides an annular passage 143 therebetween. As shown, member 142 is cast integrally with casing 141.

Mounted on each end of member 142 is a compressor cylinder 144 the outer end of which is closed by a wall 146 and a rcversely directed inwardly extending conical portion 147.

A combustion cylinder 148 is carried by webs 149 on the member 142, the outer ends of cylinder 148 extending axially into compressor cylinders 144.

A pair of piston assemblies v151] each comprises a shaft 151 reciprocally mounted in cylinder wall potrion 147 and a cylindrical member 152 carried by member 142. A compressor piston 153 and a combustion piston 154 are mounted on shaft 151. Compressor piston 153 has an outwardly projecting conical portion 153a and a reversely directed inwardly extending conical portion 154!) complementary in size and arrangement with cylinder wall portions 146 and 147 for interfitting relation therewith. This arrangement also substantially reduces the overall length of the engine.

Shaft 151 extends into the crown of piston 154, the skirt of which, in the outward position thereof, receives the member 152.

Conventional one-way valves 155 in walls 145 permit passage of air into the compressor cylinders on the inward stroke of the piston assemblies and oneaway valves "156 permit passage of air from the compressor cylinders to the passage 143. Passage 143 is divided into branches 157 leading to air charging ports 1 58 in the combustion cylinder. The combustion cylinder has exhaust ports 159 leading to an exhaust pipe 16%.

Referring to FIGURES 4 and 5, a unitary casing member 161 has pairs of arcuate passages 162 leadingfrom compressor cylinders 163 through valve-controlled ports 164 for conducting charging air to the combustion cylinder 165 through ports 166. The basic elements of the engine including compressor cylinder end walls 167 and piston assemblies 168 are closely similar to the corresponding elements in the modification of FIGURES 1, 2 and 3. It will be appreciated that the arrangement shown permits a somewhat flattened engine as shown in FIG- URE 5, and that the cylinders are open to atmosphere through openings 169 and 170. i

I claim:

1. A free piston machine comprising a generally cylindrical casing, a tubular member concentrically arranged within said casing and forming therewith a passage therebetween, a compressor cylinder constituted by each end portion of said tubular member, a combustion cylinder concentrically arranged within and supported by said tubular member, a first wall closing the outer end of each said compressor cylinder and said passage, a pair of piston assemblies each comprising a guide shaft, a compressor piston fixed to said shaft and disposed in one of said compressor cylinders, and a combustion piston fixed to said shaft and disposed in said combustion cylinder, a second wall closing each end of said combustion cylinder, each said shaft extending through said first and second walls and being supported thereby, a plurality ,of oneway valves in each said first wall and leading into one of said compressor cylinders, walls forming a pair of diametrically opposed arcuate portions of said passage, 21 series of one-way valves in each said end portion of said tubular member and leading from one of said compressor cylinders to said passage, and Walls forming an exhaust passage extending laterally from said combustion cylinder and between said passage arcuate portions, said combustion cylinder having a plurality of air charging ports communicating with said passage arcuate portions and a plurality of exhaust ports communicating with said exhaust passage.

2. A free piston machine as defined in claim 1, said passage having annular portions each surrounding one of said compressor cylinders, eachsaid series of one-way valves leading to one of said annular portions of said passage.

3. A free piston machine as defined in claim 1, said pair of arcuate portions of said passage each extending from end to end of said tubular member.

References Cited by the Examiner UNITED STATES PATENTS 1,996,974 4/1935 Pescara 23056 2,425,375 8/1947 Kilchenmann 123-46 X 2,435,233 2/1948 Mueller et al. 12351 2,501,030 3/1950 Cronstedt et a1 230--56 2,540,737 2/1951 Kalitinsky 230-56 X 2,558,444 6/1951 Kung 230-56 X MARK NEWMAN, Primary Examiner.

W. E. BUR-NS, Assistant Examiner. 

1. A FREE PISTON MACHINE COMPRISING A GENERALLY CYLINDRICAL CASING, A TUBULAR MEMBER CONCENTRICALLY ARRANGED WITHIN SAID CASING AND FORMING THEREWITH A PASSAGE THEREBETWEEN, A COMPRESSOR CYLINDER CONSTITUTED BY EACH END PORTION OF SAID TUBULAR MEMBER, A COMBUSTION CYLINDER CONCENTRICALLY ARRANGED WITHIN AND SUPPORTED BY SAID TUBULAR MEMBER, A FIRST WALL CLOSING THE OUTER END OF EACH SAID COMPRESSOR CYLINDER AND SAID PASSAGE, A PAIR OF PISTON ASSEMBLIES EACH COMPRISING A GUIDE SHAFT, A COMPRESSOR PISTON FIXED TO SAID SHAFT AND DISPOSED IN ONE OF SAID COMPRESSOR CYLINDERS, AND A COMBUSTION PISTON FIXED TO SAID SHAFT AND DISPOSED IN SAID COMBUSTION CYLINDER, A SECOND WALL CLOSING EACH END OF SAID COMBUSTION CYLINDER, EACH SAID SHAFT EXTENDING THROUGH SAID FIRST AND SECOND WALLS AND BEING SUPPORTED THEREBY, A PLURALITY OF ONEWAY VALVES IN EACH SAID FIRST WALL AND LEADING INTO ONE OF SAID COMPRESSOR CYLINDERS, WALLS FORMING A PAIR OF DIAMETRICALLY OPPOSED ARCUATE PORTIONS OF SAID PASSAGE, A SERIES OF ONE-WAY VALVES IN EACH SAID END PORTION OF SAID TUBULAR MEMBER AND LEADING FROM ONE OF SAID COMPRESSOR CYLINDERS TO SAID PASSAGE, AND WALLS FORMING AN EXHAUST PASSAGE EXTENDING LATERALLY FROM SAID COMBUSTION CYLINDER AND BETWEEN SAID PASSAGE ARCUATE PORTIONS, SAID COMBUSTION CYLINDER HAVING A PLURALITY OF AIR CHARGING PORTS COMMUNICATING WITH SAID PASSAGE ARCUATE PORTIONS AND A PLURALITY OF EXHAUST PORTS COMMUNICATING WITH SAID EXHAUST PASSAGE. 